I agree, it is hard! First of all, you can find supporting evidence in every religion to become vegetarian, especially Christianity.
However, I'm more agnostic/spiritual than anything. In philosophy class last fall, we were discussing Buddhism/Hinduism (vegetarianism is common for them) and it segued into a conversation on the potential spiritual issues with eating meat. I believe that souls are pure. My soul (or brain, or body, or whatever it is that makes you you) is uniquely me. Therefore consuming the soul/life force of other beings seemed contradictory.